Whiptail lizards, Cnemidophorous uniparens, lost all of its males somewhere along the evolutionary cycle. Females now reproduce by female-female sex. As described in Aarathi Prasad’s Like A Virgin: Exploring the Frontiers of Conception:

While the lizard is on top, it will intermittently rub its cloaca against the back of the passive female, stroking the back and neck with its jaws and forelimbs. The active female then grasps the back of the neck or shoulder of the passive female in its jaws and begins to curve and force its tail beneath the others’ tail, so that the cloacae of both are brought into close contact, somewhat as a male lizard would so in order to erect one of its two penises through its cloaca.

Once the orifices of both females are in contact, the courting female shifts its jaws to grip the lower half of the mounted females body. This forces the couple to adopt the contorted posture characteristic of mating lizards of opposite sexes.

Female-on-female Whiptail lizard action in the Amazon

Obviously questions remain. We do not know how this female-on-female sexual act causes the eggs in the passive female to “activate” as if fertilized and begin dividing into embryos, and we do not know if this pseudo-copulation is required to start the process. There is evidence of solo females reproducing in captivity without another female’s assistance.

We also do not understand how this lizard passes on DNA correctly. Typical sexuality combines half the maternal and and half the paternal DNA to give the child a new full set, but these lizards start with twice the normal DNA so halving it again gives their children a full set.

Once again, God and Mother Nature laugh at our formerly simplistic ideas of how sex works.

* A cloaca, by the way, is the name for the vent in the rear of many birds, fish, mammals, reptiles and others that serves as the single orifice for the intestines, urinary tract, and reproduction. Descriptively enough, the word comes from Latin, meaning sewer.

God certainly does delight in diversity.

(click to embiggen, if you dare)

It turns out male squid who live in the deep dark only occasionally swim past each other, and when they detect another hot little squiddy number cruising past…

…the male ejaculates a packet of sperm at the mating partner, and the packet turns inside out, essentially shooting the sperm contained in a membrane into the flesh of the partner, where they stay embedded until the female (if the shooter has been lucky) is ready to fertilize its eggs. (NYT)

Scientists in the Monterrey Bay Aquarium reviewed years of undersea videos of squid behavior and found 39 images where they could tell the sex of squid, 19 females and 20 males. Of these, 9 males and 10 females had embedded sperm. So what we learn is: squids shoot their sperm at all passing squid, male or female.

The scientific paper announcing these results, “A shot in the dark: same-sex sexual behavior in a deep-sea squid,” hints at a controversy within. Why does this happen? Scientists split on the motivation of same-sex sexuality in animals. Often, scientists assume that animals that have sex with the same-sex are just dumb, that squid, among others, cannot determine the sex of other squid. This explanation strains credulity and tears at the rationale for a procreative drive. Increasingly we understand that same-sex sexuality also serves a purpose, otherwise evolution would weed it out as wasteful misfires.

Why do male squid fire their sperm packets at other male squid? The question remains unanswered.

(FYI, calimari is just Italian for squid, but sounding more delicious, it is the more common name on restaurant menus, where you and I are most likely to run into it.)

Sadly, lifelong relationships are rare in nature, too. As the New York Times announced:

The two male chinstrap penguins had found each other in the big city. They had remained faithful. They had even raised a child. But then, not too long ago, they lost their home. Silo’s eye began to wander, and last spring he forsook his partner of six years at the Central Park Zoo and took up with a female from California named Scrappy. Of late, Roy has been seen alone, in a corner, staring at a wall.

Poor Roy. Let’s all hope he finds new love some time soon.

Charles Darwin

Researchers Nathan Bailey and Marlene Zuk provide a variety of answers in their paper Same-Sex Sexual Behavior and Evolution (pdf). It offers a wonderfully brief (7 pages of text) but highly informative academic perspective on the subject. They include a varied list of examples of how same-sex sexuality benefits various species, with some really fascinating examples.

Also included in this paper are useful suggestions for standardizing nomenclature for same-sex sexuality in animals. I don’t follow their structure, but then, I’m not aiming for the kind of linguistic precision scientific papers require.

Joan Roughgarden is an evolutionary biologist at Stanford University, and speaking from her personal experience as a transsexual, she analyzes the staggering variety we see in the animal kingdom. Sometimes too dense for the casual reader, it is nonetheless a fascinating and important book. She’s particularly insightful on the rainbow of gender variations both in animals and humans, proposing myriad new and provocative perspectives.

I love finding out how mind-bending the natural world is. God or Mother Nature or whoever is in charge certainly has a sense of humor and a profound devotion to diversity, and this book is an amazing job of trying to explain how it all works and why.

Just for fun, here is the brilliant Ricky Gervais mocking Biological Exuberance. Funny stuff, but his comment at the end about the book’s sketches is unfair, as there are plenty of photos too.

Laysan Albatross doing the breeding dance

The most readable overview on the topic comes from a long New York Times Magazine article, Can Animals Be Gay? Framing the question with a discussion of lesbian Laysan Albatross, the author does a nice job of teasing out the difference between same-sex sexuality and gay identity, and the political forces that shape the discussion.

Mr. Bonobo (photo by Ltshears via Wikimedia Commons)

Interestingly, numerous studies show that bonobos maintain a peaceful society by using sex as an alternative to conflict in their social relations. When researchers put a new and intriguing object into a cage with two female bonobos, they will often have sex with each other before they approach the gift, presumably for stress release.

Meanwhile, in humans, one of the puzzles of human physiology is why the female’s main sensory spot is located separately from the place of direct sexual contact. In males the pleasure center is at the end of the penis, which is why men can happily stick it into just about anything. This motivates men to have sex with women–he derives pleasure from putting his cock into a vagina. But the female is not similarly wired for direct pleasure in intercourse. The orgasmic functions are particularly complex, largely because of the clitoris’s location. But why?

One answer is that the male is already motivated for sex and the resulting procreation, leaving the female body free to evolve for other purposes. The famous primatologist Frans de Waal wrote in 1995, “The frontal orientation of the bonobo vulva and clitoris strongly suggest that the female genitalia be adapted for this [frontal] position.” In her book Evolution’s Rainbow, Stanford biologist Joan Roughgarden notes that,

From the standpoint of female reproduction, little is gained by placing the clitoral neurons near the vagina to further same-sex mating when males are well motivated for intercourse anyway. Instead, the pleasure neurons are shifted to a location that promotes same-sex mating and may yield more effective same-sex bonds, increasing overall Darwinian fitness at no reproductive cost.

(photo by Malloreigh via Flickr)

The mind reels. Could it be that human females evolved a frontal clitoral pleasure center because female-female sexual bonding was so vital to our development? Do human males favor the missionary position because of the ways lesbian bonding affected female bodies? And most importantly to men who want to please their partners, is the clitoris separated from the vagina for reasons that have nothing to do with men? This explains a lot of male frustration in chasing elusive female orgasms, as men are fighting a battle nature rigged for the other team. We can conclude that if men get pleasure wherever they put their penis, and women are designed to find pleasure each other, we end up with a same-sex twist on a classical formulation: men sow their seed, and women bond…with each other.

Overwhelming as it seems, every human female body may be a testament to the power and importance of same-sex bonding in women.

American Indian Head nickel, reverse

The American Bison, commonly called the Buffalo, is North America’s largest land mammal, the majestic symbol of the Great Plains, and very, very gay. American Bison males mount other males more often than they mount females, especially when young. Even when females are available, many male Bison choose other males as sexual companions. In the end, females only mate with bulls once a year, but males may mount other males several times a day during rutting season. More than a quarter of the males do not have sex with a female during rutting season, and 15 percent of females a year do not breed.

The Lakota people called these animals pte winke, or like a woman, a term they used for men who where the same way, thus tying the animal behavior to similar human behavior. Same-sex behavior is seen in European Bison, and when in heat, 15-20 percent of Water Buffalo females are mounting other females.

It appears that American Bison are not an good example for those who say homosexuality means the end of a species. I think it was human hunters who nearly achieved that feat.

Clown fish home life

The world’s coral reefs are the greatest producer of diversity on the planet, and that diversity includes gender variation.

In the wonderful Pixar movie Finding Nemo, Nemo’s mother is killed in the first scene. The rest of the movie is about the relationship between the surviving father and son clown fish.

Except that is not what happens for real clown fish. Real clown fish switch genders. As portrayed in the movie, clown fish live in a single anemone in monogamous breeding pairs of one larger female and a smaller male, along with some juveniles. However, in real clown fish lives, if the female dies, the adult male changes into a female, and one of the juveniles becomes an adult male. So… Nemo’s father should have become the larger female, and Nemo should have become his father’s, now wife’s, husband. That certainly would have made a more surprising movie.

I imagine Pixar had some lively meetings talking through the human-like story they wanted to tell using fish who have a very different idea of family building.

Most dolphins are highly experienced at sexual play. As youngsters they play in same-sex groups, and as they grow into adolescence they explore their sexuality together, forming social bonds that often last through their lives.

Pink Amazon River Dolphin

(As if swimming in a dark Amazon river isn’t weird enough, the day went all wonky on me when a larger boat full of local family and friends pulled up farther down the same beach for a barbeque. Their music blasted out of huge speakers, and I swam back to our boat to a thumping dance remix of Mama Cass’s California Dreaming. We cannot escape American culture, even deep in the Amazon.)

Heterosexual dolphin sex is achieved by swimming belly to belly, and much homosexual sex is the same, with males penetrating their male partner’s genital slit or anus. Now “genital slit” is an interesting concept, illustrating how little I understand sex in animals, even other mammals. The genitals of both dolphin sexes reside up inside a slit which closes around them to achieve that smoothly streamlined profile. This little design feature also allows sexual partners of either sex to probe the slit with their beak or fins.

In addition to vanilla sex, dolphins can be really frisky. They love to rub each other, swimming stomach to stomach or alongside so they touch, and much of this contact is with other dolphins of the same sex. Believe it or not, dolphin orgies are quite common, ranging in size from 3-4 to dozens of same-sex animals cavorting together. Sexual play among dolphins can go on for hours. Another variation is multiple males, often bonded since youth, pursuing one female, while pleasuring each other along the way.

The Amazon River Dolphin is light blue, or more amazingly, pink. They have a long narrow beak with little rows of teeth, and a bulbous forehead. Even more colorfully, Amazon River Dolphins also practice homosexual penetration of a partner’s blowhole, one dolphin above the other, the world’s only known example of nasal sex! Whoa, right?

Female Spinner Dolphins add one more position that is strikingly visual – a female positions her genital slit or vulva over a lower partner’s dorsal fin, and they swim together in that position. That has to be one wild ride.

We know that dolphins have complex communication systems and intricate social relations. It also appears that dolphin sex is about a lot more than procreation.

(All photos by Preston)

One of the most distinctive animals of the desert southwest is the Bighorn sheep. In my recent pass through Zion National Park I saw a group of them grazing their way through the scrub brush and clambering over the slickrock. It is easy to understand why the ancient Anasazi chipped pictures of these entertaining, and probably delicious, animals into the rock cliffs of the area.

The thing staunchly anti-gay Mormons can’t conceptualize is that these beautiful animals have a lot more gay sex than straight sex. Heterosexual copulation only occurs for a few days each year when the females are in heat. For the rest of the year they live their lives in same-sex groups where they court and have sex with each other, particularly when young. After signaling interest and approaching, a male mounts another male and anally penetrates him, while the mountee arches his back to facilitate entry in the manner females do. Groups of males also form huddles where they rub, nuzzle, lick, horn, and mount each other. Females play with each other in similar ways in their groups.

Intriguingly, as many as 5% of Bighorn rams are transgender, but these effeminate rams refuse to have sex with other males. These males act like females, to the point of squatting when they pee, remaining with the female group throughout their lives, and shunning sexual activity with other males in the way females do through most of the year.

The second highest Mormon leader declared at their recent conference that it is inconceivable homosexuality could be of God. Tell that to the good sheep of Zion!

(click photos to embiggen, they are beautiful creatures)

(all photos by Preston)

The tillandsia in my bathroom is usually a sculptured ball of muted greens, but today she’s all purple and pink explosions of sexual dynamism. Mother Nature in her flamboyantly tumescent glory. Phew!